作者:Akio Takuwa、Takashi Kanaue、Koichi Yamashita、Yutaka Nishigaichi
DOI:10.1039/a707609f
日期:——
The photochemical 1,3-stannyl rearrangement of allylic stannanes has been investigated. The photorearrangement of (E)-cinnamyl(triphenyl)stannane is not observed in benzene under anaerobic conditions, while the photoinduced 1,3-stannyl migration takes place in the same solvent under aerobic conditions, or in the presence of organic halides or a radical-trapping agent to give a photoequilibrium mixture of the cinnamylstannane and its branched regioisomer, 1-phenylprop-2-enyl(triphenyl)stannane, with the latter predominating. Cinnamyl(trialkyl)stannanes and their homologues also afford the corresponding branched allylstannanes under similar photochemical conditions. These 1,3-stannyl migrations proceed intramolecularly via cinnamyl π-π* excitation in competition with homolytic (cinnamyl)C–Sn bond fission. In contrast, the 1,3-stannyl migration of crotyl- and prenyl-(tributyl)stannanes is not efficient, but their triphenyl or dibutylphenyl derivatives undergo the 1,3-rearrangement via excitation of the phenyl group(s) on the tin atom to give a regioisomeric mixture of the starting linear tin compounds and the branched ones with the former predominating.
对烯丙基锡烷的光化学1,3-锡重排进行了研究。在无氧条件下,(E)-肉桂基(三苯基)锡烷在苯中未观察到光重排现象,而在有氧条件下或有有机卤化物或自由基捕获剂存在时,在同一溶剂中发生光诱导的1,3-锡迁移,形成肉桂基锡烷及其支链区域异构体、1-苯基丙-2-烯基(三苯基)锡烷的光平衡混合物,后者占主导地位。肉桂基(三烷基)锡烷及其类似物在类似的光化学条件下也得到相应的支链烯丙基锡烷。这些1,3-锡迁移通过肉桂基π-π*激发的分子内过程进行,与均裂的(肉桂基)C–Sn键断裂竞争。相比之下,巴豆基和烯丙基(三丁基)锡烷的1,3-锡迁移效率不高,但其三苯基或二丁基苯基衍生物通过锡原子上的苯基团激发发生1,3-重排,得到起始线性锡化合物和支链锡化合物的区域异构体混合物,前者占主导地位。